1. Field of the Invention
This invention relates to gate valves, and more particularly to automatically operated gate valves for use with holding or similar tanks for recreational or similar type vehicles.
2. Description of the Prior Art
Users of recreational vehicles outfitted with a water closet, tub or shower or both, and a kitchen sink are required to discharge the waste and gray water from these fixtures into onboard holding tanks that must be discharged or dumped into an approved sanitary sewer or septic system usually located in a trailer court or camp ground.
Users of recreational vehicles often find it inconvenient or difficult to dump the holding tanks into sanitary facilities because of their own physical limitations, bad weather conditions, darkness, etc. Dumping typically requires kneeling down and reaching under the vehicle for a distance of two to two and a half feet. In this position, the operator is off-balance and unable to obtain good leverage to operate a manual gate valve. This can be especially troublesome for those of slight build, the elderly and the handicapped. Moreover, while operating the gate valves, the operator is sure to be contaminated with waste should there be a failure in the waste hose, hose connection or hose clamp. In addition, gate valve operation can be especially worrisome in strange surroundings and especially annoying and frustrating in foul weather or when biting insects are at their peak.
One approach to this problem has been through the development of telescoping drain assemblies that are swiveled and telescoped to the discharge site such as revealed in Feliz U.S. Pat. No. 3,811,462 and Sargent et al. U.S. Pat. No. 4,779,650. Although these inventions attempt to solve the piping problem between the discharge line of the vehicle and the discharge point, neither of them address the problem of valve control since both of these inventions continue to use manually operated valves to open and close the discharge lines.
Kemper et al U.S. Pat. No. 4,214,324 and Perez U.S. Pat. No. 4,693,447 disclose waste dump valves that are electrically controlled for use in aircraft and railroad cars respectively. Hilde, Jr. U.S. Pat. No. 3,375,025 is directed to a pneumatic valve mechanism for use with a mobil system for evacuating and recharging portable commodes.
Pierson U.S. Pat. No. 3,941,349 is directed toward the development of electromechanically actuated gate valves. Pierson's inventions, however, have several shortcomings and problems. First, all of Pierson's mechanisms for controlling the gate valve are contained within the housing of the gate valve itself. As such, it is not possible to convert an existing manual valve to a mechanically operated device. All the vehicle owner can do is to remove the manual valve and replace it with one of Pierson's electromechanically operated valves. Further if the electromechanical mechanism of the Pierson valve breaks down, it is impossible to repair it with out removing it from the drainage line--a process which requires replacement of a portion of the drainage lines in addition to the repair or replacement of the valve itself.
Pierson's solenoid driven valves are spring biased so as to remain in the closed position unless the solenoid is electrically actuated. As a result, Pierson's solenoid devices must draw current continuously while the holding tank is being emptied thereby adding to the cost of operation and increasing the potential for failure as a result of electrical short or burnout. Such continuous operation also increases the chance for an electrical fire. Moreover, Pierson's closed biased solenoid valves do not allow the valve to be left in an open position, even by manual operation. In many instances this is the preferred position, especially when the vehicle has been permanently parked and the drainage line hooked up to the sanitary sewer. In such a setting, the drainage line is left open without further consideration. Using the Pierson valve, the vehicle user must periodically open the gate valve to drain the holding tanks even when the vehicle is in a parked mode and connected to a sanitary sewer. Such additional operation tends only to shorten the life of the Pierson valve. Because Pierson's solenoid valves effectively have only a fully opened or closed position, it is impossible to adjust the volume of discharge from the holding system. In the event of a power failure, the user of a Pierson solenoid valve must resort to manual operation of the valve in order to empty the holding tanks.
Pierson has also developed motor driven direct drive and gear drive valves. Such motor driven valves are more complex than the solenoid valves thereby increasing the potential for malfunction. Since the drive mechanisms are contained within the valve housing, the only way to repair such valves is by removing them from the drainage line, which, as we have seen, is costly since portions of the drainage line must be replaced along with possibly the valve itself.